Investigation On Chemical Mechanical Polishing Slurry Of Ru As Novel Diffusion Barrier Material

With the development of the integrated circuit towards the high integration degree,the feature size of the device is getting smaller and smaller.When the technology node is under14 nm,we need a new kind of material with high melting point and low resistivity to decrease the delayed time during the signal going through the interconnecting wire.Thus,to compare with Ta/TaN,Ru owns obvious advantages as the material of copper interconnect barrier.At the same time,the direct plating of the copper without seed layer can be finished by Ru,which can greatly improve the reliability of interconnecting wire.Because of the lack of researching about Ru,it's important to study the slurry of chemical mechanical polishing.In order to obtain a set of ideal slurry ratio,the paper took the domestic and foreign science and technology as the background.Firstly,under the condition of 150ml/min slurry flow rate,2psi working pressure,60rpm/65rpm polishing head and the polishing disc speed,the paper investigated the influence of abrasive concentration on Ru chemical mechanical polishing.As a result,the polishing rate of Cu and Ru could satisfy the requirement when the concentration of silica sol was 4%.Compared with the abrasive concentration of 20%,the concentration of slurry is relatively stable,reducing the cost.Then it researched how oxidant such as KIO₄ and FA/O I to influence the polishing rate and static corrosion of Cu and Ru.After studying,with the rising concentration of KIO₄,the polishing rate presented increasing trend.And only when the concentration of KIO₄ reached 0.02 mol/L and which of FA/O I reached 3 ml/L could them satisfy the requirements of both two materials polishing rate selection ratio nearly reached 1.And after researching the surface corrosion situation of Cu and Ru by electrochemical test,it showed that 3ml/L FA/O I could lightly relief the serious galvanic corrosion between Cu and Ru.After that,it also studied the influence of I non-ionic surfactant on Ru CMP,and the result showed that when the concentration of this kind of active agent reached 10 ml/L,the polishing rate could satisfy the requirements and be with better surface roughness after polishing,meanwhile owning better wetting property and stable slurry.Finally,it deeply researched the mechanism about Ru chemical mechanical polishing.It showed that under the alkaline condition,Ru reacted with IO₄^-to form RuO₄^2-,and then reacted with FA/O I to form soluble amine salt——?[R?NH₃?₄]?RuO₄?₂?--to remove Ru.